/*
 * Copyright (C) 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;

/**
 * Implementation of {@link ImmutableListMultimap} with no entries.
 * 
 * @author Mike Ward
 */
@GwtCompatible(serializable = true)
class EmptyImmutableSetMultimap extends ImmutableSetMultimap<Object, Object> {
    static final EmptyImmutableSetMultimap INSTANCE = new EmptyImmutableSetMultimap();

    private EmptyImmutableSetMultimap() {
        super(ImmutableMap.<Object, ImmutableSet<Object>> of(), 0);
    }

    private Object readResolve() {
        return INSTANCE; // preserve singleton property
    }

    private static final long serialVersionUID = 0;
}
